[osg-users] osgText 3.6.3 crash

[Trajce Nikolov NICK]

Hi Robert,

we are experiencing some crashes in our sim software. And I know you will
not like this post since I can not produce minimal case exercising this
issue - I tried to mimic the sim code into one simple app but in this
minimal app all works just great. So I will try to explain and count on you
with hints

The environment is multithreaded:
- high res thread updating labels guarded by mutex
- the osg threads with update callbacks on osgText::Text that is setting
the labels with setText(...) guarded by mutex

The env is XUbuntu 18, NVIDIA GTX 1080

And the crash happens at
Text::drawImplementationSinglePass ln: 1151
glyphquad._primitives->draw(state, usingVertexBufferObjects);

which furthers

DrawElementsUShort::draw ln: 266

if (_numInstances>=1) state.glDrawElementsInstanced(mode, size(),
GL_UNSIGNED_SHORT, (const GLvoid *)(ebo->getOffset(getBufferIndex())),
_numInstances);
else glDrawElements(mode, size(), GL_UNSIGNED_SHORT, (const
GLvoid *)(ebo->getOffset(getBufferIndex())));

_numInstances is 0 when the crash happens so the crash happens here:

glDrawElements(mode, size(), GL_UNSIGNED_SHORT, (const GLvoid
*)(ebo->getOffset(getBufferIndex())));

Any clue or at least a thought when this can happen? Mean while I will
continue testing and will really try again to make a small app reproducing
this behavior

Thanks a bunch as always!

Cheers,
Nick

[Robert Osfield]

Hi Nick,

There are plenty of ways mutlti-thread setting of Text labels could
cause problems if the threads reading from the Text are running in
parallel to the ones setting it. A mutex "might" help but it could
easily be done in the wrong way. If you are modifying text
dynamically then you should set the DataVariance to DYNAMIC. However,
adding mutex and using DataVariance of DYNAMIC might protect things if
you do it all right but performance issues can easily become dominant
as it can easily stall the various threads.

It may be that trying to dynamically update Text is simply the wrong
solution for your application. It might be that writing your own
custom shader to implement text is the better thing to do.

Robert.




On Wed, 12 Sep 2018 at 13:24, Trajce Nikolov NICK

Post by Trajce Nikolov NICK
Hi Robert,
we are experiencing some crashes in our sim software. And I know you will not like this post since I can not produce minimal case exercising this issue - I tried to mimic the sim code into one simple app but in this minimal app all works just great. So I will try to explain and count on you with hints
- high res thread updating labels guarded by mutex
- the osg threads with update callbacks on osgText::Text that is setting the labels with setText(...) guarded by mutex
The env is XUbuntu 18, NVIDIA GTX 1080
And the crash happens at
Text::drawImplementationSinglePass ln: 1151 glyphquad._primitives->draw(state, usingVertexBufferObjects);
which furthers
DrawElementsUShort::draw ln: 266
if (_numInstances>=1) state.glDrawElementsInstanced(mode, size(), GL_UNSIGNED_SHORT, (const GLvoid *)(ebo->getOffset(getBufferIndex())), _numInstances);
else glDrawElements(mode, size(), GL_UNSIGNED_SHORT, (const GLvoid *)(ebo->getOffset(getBufferIndex())));
glDrawElements(mode, size(), GL_UNSIGNED_SHORT, (const GLvoid *)(ebo->getOffset(getBufferIndex())));
Any clue or at least a thought when this can happen? Mean while I will continue testing and will really try again to make a small app reproducing this behavior
Thanks a bunch as always!
Cheers,
Nick
--
trajce nikolov nick
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osg-users mailing list
http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org

[Trajce Nikolov NICK]

Hi Robert,

That was the right hint and I must admit that I always forget it :-).
Setting the datavaraiance to osg::Object::DYNAMIC fixed the crash! As for
the other hints re performance, this is for sort of DEBUG mode for the sim
so we are ok, but thanks for these as well!

Post by Robert Osfield
Hi Nick,
There are plenty of ways mutlti-thread setting of Text labels could
cause problems if the threads reading from the Text are running in
parallel to the ones setting it. A mutex "might" help but it could
easily be done in the wrong way. If you are modifying text
dynamically then you should set the DataVariance to DYNAMIC. However,
adding mutex and using DataVariance of DYNAMIC might protect things if
you do it all right but performance issues can easily become dominant
as it can easily stall the various threads.
It may be that trying to dynamically update Text is simply the wrong
solution for your application. It might be that writing your own
custom shader to implement text is the better thing to do.
Robert.
On Wed, 12 Sep 2018 at 13:24, Trajce Nikolov NICK

Post by Trajce Nikolov NICK
Hi Robert,
we are experiencing some crashes in our sim software. And I know you

will not like this post since I can not produce minimal case exercising
this issue - I tried to mimic the sim code into one simple app but in this
minimal app all works just great. So I will try to explain and count on you
with hints

Post by Trajce Nikolov NICK
- high res thread updating labels guarded by mutex
- the osg threads with update callbacks on osgText::Text that is setting

the labels with setText(...) guarded by mutex

Post by Trajce Nikolov NICK
The env is XUbuntu 18, NVIDIA GTX 1080
And the crash happens at
Text::drawImplementationSinglePass ln: 1151

glyphquad._primitives->draw(state, usingVertexBufferObjects);

Post by Trajce Nikolov NICK
which furthers
DrawElementsUShort::draw ln: 266
if (_numInstances>=1) state.glDrawElementsInstanced(mode, size(),

GL_UNSIGNED_SHORT, (const GLvoid *)(ebo->getOffset(getBufferIndex())),
_numInstances);

Post by Trajce Nikolov NICK
else glDrawElements(mode, size(), GL_UNSIGNED_SHORT, (const

GLvoid *)(ebo->getOffset(getBufferIndex())));

Post by Trajce Nikolov NICK
glDrawElements(mode, size(), GL_UNSIGNED_SHORT, (const GLvoid

*)(ebo->getOffset(getBufferIndex())));

Post by Trajce Nikolov NICK
Any clue or at least a thought when this can happen? Mean while I will

continue testing and will really try again to make a small app reproducing
this behavior

Post by Trajce Nikolov NICK
Thanks a bunch as always!
Cheers,
Nick
--
trajce nikolov nick
_______________________________________________
osg-users mailing list

http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
_______________________________________________
osg-users mailing list
http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org